Windows ERROR: Problem running `fmtutil-sys --all` to rebuild format tree.

[reckoner]

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

No response

Steps to reproduce

No response

Actual behavior

No response

Expected behavior

No response

Your environment

No response

Quarto check output

Quarto 1.9.37
[>] Checking environment information...
Quarto cache location: C:\Users\reckoner\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
Pandoc version 3.8.3: OK
Dart Sass version 1.87.0: OK
Deno version 2.4.5: OK
Typst version 0.14.2: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
Version: 1.9.37
Path: D:\quarto_book.venv\Lib\site-packages\quarto_cli\bin
CodePage: 1252

[>] Checking tools....................OK
TinyTeX: v2026.04
Chromium: (not installed)
Chrome Headless Shell: (not installed)
VeraPDF: (not installed)

[>] Checking LaTeX....................OK
Using: TinyTex
Path: C:\Users\reckoner\AppData\Roaming\TinyTeX\bin\windows
Version: 2026

[>] Checking Chrome Headless....................OK
Using: Chrome found on system
Path: C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe
Source: Windows Registry

[>] Checking basic markdown render....OK

[>] Checking R installation...........(None)

  Unable to locate an installed version of R.
  Install R from https://cloud.r-project.org/

[>] Checking Python 3 installation....(None)

  Unable to locate an installed version of Python 3.
  Install Python 3 from https://www.python.org/downloads/

[>] Checking Julia installation...

[reckoner]

I cannot render my pdf anymore. I'm using TinyTex which is the latest version. I read

https://github.com/quarto-dev/quarto-cli/pull/10209/commits

and reinstalled per those suggestions. I went directly to the tinytex bin directory and ran all the update commands but
it still keeps wanting to update tlmgr even though I updated manually from the tinytex directory.

I'm stuck. :(

Rendering PDF
running xelatex - 1
  This is XeTeX, Version 3.141592653-2.6-0.999998 (TeX Live 2026) (preloaded format=xelatex)
   restricted \write18 enabled.
  entering extended mode

updating tlmgr

updating existing packages
finding package for tikzlibrarytopaths.code.tex
> 1 package to install
> installing pgf (1 of 1)
WARN: Error encountered when rendering files
ERROR: Problem running `fmtutil-sys --all` to rebuild format tree.

Stack trace:
    at renderFiles (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:136608:49)
    at eventLoopTick (ext:core/01_core.js:179:7)
    at async renderProject (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:137151:23)
    at async _Command.actionHandler (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:142481:24)
    at async _Command.execute (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:102102:7)
    at async _Command.parseCommand (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:101979:14)
    at async quarto4 (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:187653:5)
    at async file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:187681:5
    at async file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:187536:14
    at async mainRunner (file:///D:/quarto_book/.venv/Lib/site-packages/quarto_cli/bin/quarto.js:187538:5)

[mcanouil]

@reckoner Please edit your original post with all the informations requested.

---

You can share a self-contained "working" (reproducible) Quarto document using the following syntax, i.e., using more backticks than you have in your document (usually four ````).
See https://quarto.org/bug-reports.html#small-is-beautiful-aim-for-a-single-document-with-10-lines.

If you have multiple files (and if it is absolutely required to have multiple files), please share as a Git repository.

R	Python
````qmd --- title: "Reproducible Quarto Document" format: html engine: knitr --- This is a reproducible Quarto document. {{< lipsum 1 >}} ```{r} x <- c(1, 2, 3, 4, 5) y <- c(1, 4, 9, 16, 25) plot(x, y) ``` {#fig-placeholder} {{< lipsum 1 >}} The end after @fig-placeholder. ````	````qmd --- title: "Reproducible Quarto Document" format: html engine: jupyter --- This is a reproducible Quarto document. {{< lipsum 1 >}} ```{python} import matplotlib.pyplot as plt x = [1, 2, 3, 4, 5] y = [1, 4, 9, 16, 25] plt.plot(x, y) plt.show() ``` {#fig-placeholder} {{< lipsum 1 >}} The end after @fig-placeholder. ````

Additionally and if not already given, please share the output of quarto check within a code block (i.e., using three backticks ```txt), see https://quarto.org/bug-reports.html#check.